The bill was a marquee piece of legislation for Governor Jerry Brown and Democratic state leaders in advance of the Paris climate talks.

The oil industry targeted business-friendly Democrats in the legislature to kill the gasoline-related portion of the bill, sparking a major intra-battle in the final weeks before the vote. Ultimately, the industry was successful and the oil-related part of the bill was removed in its allowing it to pass in a weakened state with no petroleum restrictions.

Big oil might be on the right side of the shareholder reports, but were on the right side of history, said Senate leader Kevin de León, one of the key authors of SB-350, on the defeat of the oil restrictions in the bill. Ultimately, California is going to demand that an industry which represents most of the problem has an economic and moral duty to be part of the solution.

Recently required disclosures to the California secretary of state reveal that The Western States Petroleum Association, a trade group for the oil industry, was the states single largest spender when it came campaigning in the state Capitol last year, reporting $10,949,149.83 in total payments to influence. $6.7m of that took place in the third quarter, and an additional $1.6m was spent in the final quarter, the periods when SB-350 was hotly contested.

That was an increase over the almost $9m it spent in 2014, and $4.7m spent in 2013.

Big Oil is the new robber barons for us in the California legislature, said Jamie Court, president of Consumer Watchdog. If there is any question of this, it was confirmed in the last days of the the legislative session.

Included in most recent filings from the trade group are meals at Spago, a restaruant in Maui, Hawaii, for nine legislators, racking up tabs of up to $182.28 each. Oil companies also lobbied individually on SB-350 and other issues. That event took place during a controversial week-long conference in Hawaii sponsored by the California Independent Voter Project that brings together California legislators with corporate event sponsors.

Chevron Corporation and subsidiaries spend nearly $4m in 2015, while on the other side of the issue, billionaire environmentalist Tom Steyers Climate Action spent nearly $2m advocating in support of change legislation and other causes.

Despite the disclosures, the exact nature of much lobbying spending remains cloudy because it can be reported under the catch-all category of payments to influence, which accounted for $6.1m of the Western States spending, or 69% of the spending by the top ten lobbyists in Californias state capital, Sacramento, according FPPC information provided by Consumer Watchdog.

Those rules are changing later this year, and will require itemization of payments listed as other, but would not require third-party vendors to list specific activities.

Theres still a lot they can hide through third party expenditures, but at least were on the right track, said Court.